Automatic variable speed transmission



Feb. 7,.1939. w. HARTZ I AUTOMATIC VARIABLJVE SPEED TRANSIIISSION Filed July 23, 193 2 Sheets-Sheet l I I v INVENTOR.

' Fly/[m 9141a;

I AfiORNEY! Feb. 7,1939 w'. HARTZ 2,145,927

AUTOMATIC V-ARIABLE SPEED TRANSMISSION 7 Filed July 23, 1936 2 Sheets-Sheet 2 w arm;

A ORNEY.

I Patented Feb. 1, 1939 AUTOMATIC VARIABLE SPEED 1 TRANSMISSION William Hartz, Detroit, Mich.

- Application July 23, 1936, Serial No. 92,167

' '7 Claims. (01. 74- 3365) This invention relates to variable speed transmissions and in particular to means; for changing gear ratios in a type of transmission generally adapted for use in motor vehicles and the like. One object of the invention is to provide, in combination with a transmission, simple, inexpensive means for automatically varying the gear 'ratiobetween a driving shaft and a driven shaft mresponsive to the. speed of the driven shaft whereby the speed of the driving shaft is maintained substantially constant-during the change of gear ratio.

' u Another object of the invention is to provide a simple compact inexpensive centrifugal controlled ratchet type automatic gear selector for 'I transmissions.

Another object of the, invention is to provide a constant mesh variable speed transmission for automotive vehicles wherein a plurality of changes in forward speed ratios may be accomplished automatically under control of the cen- I itrifugalforce of thedriven shaft thereof.

Other objects of the invention will become apparent byreference to the following detailed description taken in connection with the accompanying I drawings, in which:

Fig. 1 is'a longitudinal sectional view of a transmission embodying the invention taken on the line l-l of Fig. 2.

' Fig. 2 is a cross sectional view taken on the line 22 of Fig. 1.

wFig. 3 is an end elevational view of a ratchet "type automatic gear selector unit embodying the invention taken'on the line 33 of Fig. l.

-Fig. 4 is a fragmentary sectional view of a torque impactabsorbing mechanismwhich may 1 'beused with the invention. I Fig. 5 is an enlarged sectional view taken on the line 5-5 of Fig. 2 showing the forward gearing of the transmission disclosed in Fig. 1 with the ratchet type automatic gear selector engaged I v inits low speed position.

Fig. 6 is a fragmentary sectional view taken ;on the line 66 of Fig. Blocking in the direction indicated by the arrows.

Fig. '7 is an exploded view in perspective showing more or less diagrammatically the relation between a cam and a set of high speed ratchet stops employed in the invention.

Fig. 8 is an exploded view in perspective similarto Fig. '7 indicating an alternate cam and V ratchet construction.

. numerals refer to like and corresponding parts 1 throughout the several views, the embodiment of the invention disclosed comprises, in general, a housing lo, a drive shaft II which is preferably connected to a source of power such as an automotive engine through a suitable clutch in I the usual manner, an idler shaft l2, and a driven shaft l3 which may be connected through any suitable torque impact absorbing mechanism l4, if such is desirable, and a universal joint, not

shown, to the propeller shaft of a motor vehicle;

the said shafts ll, l2 and I3 being inter-connected by a plurality of gears as hereinafter described.

The drive shaft II is journaled at one end in the housing by means of the bearing and. has the other end thereofjournaled through the front of the said housing I0 by means of the bearing iii. A driving gear I! having a shift collar i8 is splined on the drive'shaft II for rotation therewith and longitudinal movement thereon. The said driving gear I1 isshown in Fig. 1 engaged with the gearing 2' of the triple idler gear 21; however, it may be shifted by means of the usual shift fork IS on a shaft 20 slideably mounted in the top plate 2| of the housing H) to a neutral position as indicated by the dash and two dot lines 22 or into a reverse positon as indicated by the dash and dot lines 23. The shift fork l9 and shaft 2|] may be moved to the desired position by any manual means not shown; however, it is preferable to prevent shaft 20, shift fork l9 and driving gear I! in the position into which they are shifted.

The idler shaft [2 is mounted in each end of the housing 10 and is preferably keyed against rotation therein. The idler shaft I2 is suitably shouldered to accommodate a triple idler gear 21 rotatably mounted thereon by such suitable means as the roller bearings 28. The said triple idler gear 21 is preferably formed with the low speed gearing 21!], intermediate speed gearing 2H and high speed gearing 212 thereof all rotating at the same speed and driven by the driving gear I1 when the said driving gear I! is meshed with the intermediate speed gearing 21 l thereof.

Although the embodiment of the invention disclosed herein indicates that the driving gear I! meshes with the intermediate speed gearing 21! of the triple idler gear 21, the said driving gear ll may be arranged to mesh with the low speed gearing 210 or the high speed gearing 212 if lower or higher engine speeds are desirable.

The driven shaft I3 is journaled at one end in the housing In by means of the bearing 29 and has the other end thereof journaled through the rear of the said housing Hibymeans of thebearing 30. The driven shaft |3 is suitably shouldered to accommodate a low speed driven gear 3| rotatably mounted thereon by such suitable means as the roller bearings 32. The said low speed driven gear 3| is provided with an axially extending collar 3||l which serves as a shaft upon which intermediate speed driven gear 33 is rotatably mounted by such suitable .means as the roller bearings 35. The said intermediate speed driven gear 33 is provided with an .axially extending collar 338 which serves as a shaft upon which high speed driven gear 35 is rotatably mounted by such suitable means as the roller bearing 36. Thus, the low speed driven gear 3|, intermediate speed driven gear 33 and high speed driven gear 35 are adapted to freely rotate in respect to each other and the driven shaft l3. As shown in Fig. 5, the end faces of the axially extending collars 3| ll and 330 and the rear face of thehigh speed driven gear 35 are in radial alignment in respect to each other. A reverse gear 31 is keyed on the driven shaft |3 in a position to be readily engaged by the driving gear as hereinbefore described.

A ratchet type automatic gear selector unit 38 is mounted on the driven shaft 3 and keyed thereto by a key 39 for rotation therewith and is located in operating spaced relation to the end faces of the said axially extending collars 3||l and33i and the rear face-of the high speed driven gear 35. The direction of rotation of the gear selector 38 and the driven shaft I3 during low, intermediate and high forward speeds is shown by the arrows 40 in Fig. 3.

The automatic gear selector unit 38 is cylindrical in shape and is provided with one or more preferably rectangular radially disposed chases 4| equally spaced in respect to each other around the periphery of the said gear selector unit 38, three of the said chases 4| being provided in the embodiment of the invention shown in the drawmgs. unit 33 shown in the drawings, a plurality of axially disposed low speed ratchet stops 42 are provided circumferentially spaced at 120 degrees in respect to each other at a radius from the center of the driven shaft |3 which will permit the same'to register with and engage the end of the collar 3||l of the low speed gear 3| at the notches 43 therein. The said .low speed ratchet stops 42 are axially mounted for reciprocation. in suitable axial apertures in the said gear selector unit 38 and are constantly urged toward and into engagement with the end of the low speed collar m of the low speed gear 3| by means of suitable springs 44, see Fig. 6.

The said notches 43 in the end face of the low speed collar 3|ll of the low speed gear 3| are suitably beveled and are radially and circumnferentially located to receive simultaneously the complementarily beveled ends of the low speed ratchet stops 42 which are constantly urged into registry with said notches 43. The low speed ratchet stops 42 may be provided in any number and size with a like or greater number of cooperating notches 43 provided in the said low speed collar 3| 0.

A plurality of axially disposed intermediate speed ratchet stops 45 each having a beveled cam follower 46 integral therewith are suitably located and mounted for reciprocation in axially disposed apertures in the said gear selector unit 38 so as to permit a cam 4'! mounted for radial reciprocation in the rectangular radially disposed chases In the embodiment of the gear selector 4| to engage the said cam follower 46 during the radial reciprocation of the said cam 41 as hereinafter described. The said intermediate speed ratchet stops 45 are constantly urged toward and. into engagement with the end of the intermediate speed collar 33!) of the intermediate speed gear 33 by means of suitable springs 48.

The said intermediate speed collar 330 is provided with a plurality of suitably beveled notches '49 in the end face thereof radially and located to receive simultaneously the complementarily beve'led ends of the intermediate speed ratchet stops '45 which'are constantly urged into registry with the said beveled notches 49 under the control of the cam 47. One intermediate speed ratchet stop 45 is provided for each radial reciprocating cam il; however, a like or greater number of cooperating notches 49 may be providedin the said intermediate speed collar 330.

A plurality of axially disposed high speed ratchet stops 50 each having a beveled cam follower 5| integral therewith are suitably located and mounted for reciprocation in axial apertures in the said gear selector unit 38 so as to permit the cam 47 mounted for radial reciprocation in 'the' radially disposed chases 4| to engage the said cam follower 5| during the radial reciprocation of the said cam 41 hereinafter described. The said high speed ratchet stops 50 are constantly urged toward and into engagement with the high speed gear 35 by means of suitable springs 48.

By referring to Fig. '7, the relation between the radially disposed cam 41, the axially disposed intermediate speed ratchet stops 45, and the axially disposed high speed ratchet stops 50 is readily observed. 7

The said high speed gear 35 is provided with a plurality of suitably beveled notches 52 in the rear face thereof radially and circumferentially located to receive simultaneously the complementarily beveled ends of the high speed ratchet stops 53 which are constantly urged into registry with the said beveled notches 52 under control of the cam 41. One high speed ratchet stop 50 is provided for each radially reciprocating cam '41; however, a like or greater number of cooperating notches 52 may be provided in the said high speed gear 35.

The cam 41 mounted for radial reciprocation in each of the said radially disposed chases 4| is preferably rectangular in shape and provided with an integral inwardly extending rectangular .finger 413 which is beveled at the end thereof forming a cam surface against which the complementary beveled cam followers 46 and 5| of the intermediate and high speed ratchet stops 45 and 5|] respectively contact when the said cam 41 reciprocates radially.

The said cam 41 and ratchet stops 45 and 53 may be constructed as shown in Fig. 8 in which event the cam 4100 illustrated more or less diagrammatically therein is wider than the cam 47 and is provided with two radially spaced parallel inwardly extending fingers 470 beveled on their ends to form cam surfaces. When cams 4730 are substituted for cams 41, intermediate and high speed ratchet stops 45D and 500 are provided with dual cam followers 460 and 5H] respectively complementarily beveled in respect to the beveled surface of the cam fingers 410.

Each cam 4'! is provided with an axially disposed bore preferably in the main body portion thereof into which a spring 72 and ball detent 53 are positioned in such a manner as to constantly urge the ball detent 53 axially for rev r p 2,145,927 leasable engagement in suitably spacednotches 54, 55 and 56' in'the wall of the radially disposed chases 4| during the radial movement" of the said'cam 41,]th'us permitting the cam 41 to reciprocateradially in intermittent steps in accordance with" the centrifugalor centripetal forces I 55 and 56 is suchas will stop the movement of 'the'radially reciprocating cam 41 in such posi tions as will control the low speed, intermediate speed and high speed gear ratios respectively betweenthe idler shaft 1 2 and the driven shaft 13.

'- A suitable preferably conical spring 51 having Y one'end. thereof centered around a tab 58 on the outer end of each radially disposedcam 41 reaots against a cover plate .59 secured by the' bolts .60 'on' the periphery of the said gear selector unit 38 and provides the centripetal force 1 fto" constantly urge the said cam 41 to its low 7 '20 speed position as indicated in Fig. 5 with the intermediate speed ratchet stops 45andthe high 7' .speedratchetstops 50 controlled by the said cam -41 out of engagement with the intermediate speedgear 33 and high speed gear 35 respectively.

The weight of the cam 41 and the rate of rotation' of the gear selector unit 38 on the driven shaft' I3 provides a variable centrifugal force which overcomes the centripetal force applied to the cam 41 by the conical spring 51, which spring 9 compressed by the radial movement of the cam 41.

ofie'rsa greater resistance tocompression as itis A suitable torque impact mechanism 14 shown inFigs. 1 and 4 may be used if desired to reduce the torque impact when the automatic gear selector 38 changes from a low to intermediate ,or from intermediate to high'speed gears. The I embodiment of the torque impact mechanism 1 m'ent' 62. A suitablespringBB circumferentially w disposed in the said notches 66 cushions the im' the 'icup 63 when torqueimpact occurs. notches 66may be made circumferentially longer I4 indicated in the drawings comprises a cylindrical element 62 keyed on the end of the driven shaft I3,.a cylindrical cup 63 mounted for rotation therearound and a drivenshaft I36 on 'said. cup' 63 rotatably mounted through a supplementary housing Hill by means of a suitable bearing 64. A plurality of inwardly disposed teeth 65 within the said cup 63 are positioned in suitable notches 66- in the periphery of the cylindrical element 62 which engage the radially disposed shoulders 61 .of the said cylindrical elepact between the said cylindrical element 62 and The I 7 than shown in Fig. 4 and a spring 68 may be inin either direction.

serted on both sides of thesaid teeth 65 within thenotches 66 for reducing the torque impact that occurs when the speed of'the driven shaft is suddenly increased or decreased when rotating The operation of the automatic variable speed transmission disclosed herein is manual for shifting from neutral to low or reverse and'is accomplishd in the conventional manner. However,

once shifted into low gear, the automatic gear t0:low forward speed is accomplished'in the conventional manner by manually causing the driving gear 11 splined on the drive shaft H to fmesh with the gearing 21l of the triple idler gear 21. The triple idler gear 21 rotates the low speed gear 3|, intermediate speed gear 33 and high speed gear 35 simultaneously, all at The location of the said notches 55,

their various speeds freely in respect to each other and the driven shaft 13 on which they are rotatably mounted. d

The gear selector unit 38 keyed on the driven shaft l3 for driving the same is normally rotated by the low speed gear 3| with the low speed ratchet stops 42 thereof constantly urged into engagement with the collar of the low speed gear 3| by the springs 44. -As the speed of the driven shaft [3 is increased, the centrifugal force on the said cams 41 overcomes the centripetal force exerted thereon by the springs 51 and the said cams 41 move radially outward thereby permitting the intermediate speed ratchet stops 45 to engage the intermediate speed gear 33 which then drives the driven shaft 13. As the speed of the driven shaft [3 is again increased, the additional centrifugal force on the said cams 41 overcomes the centripetal force. exerted thereon by the springs 51 and the said cams 41 move radially outward thereby permitting the high speed ratchet stops 50 to engage the high speed gear 35 which then drives the driven shaft l3. The converse is true as the speed of the driven shaft is on the decrease rather than on the increase.

Because of the fact that the ratchet stops 42, 45 and 50 are beveled and engage complementarily beveled notches in the gearing 3|, 33 and 35, the gears that are not working at any particular stage of operation of the gear selector unit idle with the idler gear 21L When the power is relieved on the drive shaft H, the transmission serves as a free wheeling unit. However, inasmuch as free wheeling is not desirable at high speeds, the high speed ratchet stops 50 preferably may be made with square or rectangular ends and the complementary notches 52 in the high speed gear 35 may be square or rectangular, which construction eliminates free wheeling during high speeds when the high speed gear 35 is engaged by the gear selector unit 38. Fig. 9 indicates anti-free wheeling construction for high speeds in which the high speed gear 35 is provided with rectangular notches 520 which accommodate the rectangular ended high speed ratchet stops 560 of the gear selector unit 38.

When the driving gear I1 is manually shifted into engagement'with the reverse gear 31, 'the forward speed gears idle with the idler gear 21 and the ratchet stops 42 click by the notches 43 in the low speed gear 3 I.

Although but one embodiment of the invention has been disclosed and described in detail, it will be understood that various changes including the size, shape, arrangement and detail of parts thereof may be made without departing from the spirit of the invention, and it is not my intention to limit the scope of the invention other than by the terms of the appended claims.

I claim:

1; In a variable speed transmission, a drive shaft, an idler shaft and a driven shaft, a driving gear on said drive shaft, a triple idler gear on said idler shaft driven by said driving gear; low, intermediate and high speed driven gears in constant mesh with said triple idler gear simultaneously rotatable thereby at various speeds in respect to each other mounted in nested relationship to each other on said driven shaft for free rotation in respect thereto, an automatic gear selector unit mounted on said driven shaft adapted to rotate the same, axially movable means in said gear selector unit normally urged into engagement with said driven'gears, and radially reciprocating cam means movable responsive to the speed of said driven shaft adapted to permit only one of said driven gears. to be engagedby said axially movable means at any onetime.

2. In a variable speed transmission, a drive shaft, an idler shaft and a driven shaft, a driving gear on said drive shaft, a triple idler gear on said idler shaft driven by said driving gear; low, intermediate and high speed driven gears in constant mesh with said triple idler gear simultaneously rotatable thereby at various speeds in respect to each other mounted in nested relationship to each other on said driven shaft for free rotation in respect thereto, the said nested driven gears having one end face thereof in radial alignment in respect to each other, axially disposed notches in the said radially aligned ends of said nested driven gears, an automatic gear selector unit keyed on said driven shaft adjacent said aligned ends of said driven gears, means in said gear selector unit axially urged into engagement with said notches in said driven gears, and means responsive to the speed of the driven shaft adapted to disengage one or more of said means axially urged into engagement with said driven gears whereby to permit the said driven shaft to be rotated by the highest speed driven gear not disengaged.

3. In a variable speed transmission, a drive shaft, an idler shaft and a driven shaft, a driving gear on said drive shaft, a triple idler gear on said idler shaft driven by said driving gear; low, intermediate and high speed driven gears in constant mesh with said triple idler gear simultaneously rotatable thereby at various speeds in respect to each other mounted in nested relationship to each other on said driven shaft for free rotation in respect thereto, the said nested driven gears having one end face thereof flush in respect to each other and a plurality of beveled notches in said end faces of said driven gears, an automatic gear selector unit keyed on said driven shaft adjacent to said notched end faces of said driven gears, and axially disposed ratchet stops in said gear selector unit adapted to selectively engage said driven gears responsive to the speed of said driven shaft whereupon said driven shaft is rotated by the highest speed driven gear engaged by said ratchet stops of said gear selector unit.

4. In a variable speed transmision, a drive shaft, an idler shaft and a driven shaft, a driving gear on said drive shaft, a triple idler gear on said idler shaft driven by said driving gear; low, intermediate and high speed driven gears in constant mesh with said triple idler gear simultaneously rotatable thereby at various speeds in respect to each other mounted in nested relationship to each other on said driven shaft for free rotation in respect thereto, the said nested driven gears having one end face thereof flush in respect to each other and a plurality of beveled notches in said end faces of said driven gears, an automatic gear selector unit keyed on said driven shaft adjacent to said notched end faces of said riven gears, axially disposed low speed ratchet stops in said gear selector unit normally engage in beveled notches in said low speed driven gear, and intermediate and high speed axially disposed ratchet stops in said gear selector unit adapted to selectively engage said driven gears responsive to the speed of said driven. shaft whereupon said driven shaft is rotated by the highest speed driven gear engaged by said ratchet stops of said gear selector unit.

5. In a variable speed; transmission, a drive shaft, an idler shaft and a driven shaft, a driving gear on said drive shaft, a triple idler gear on said'idler shaft driven by said driving gear; low, intermediate and high speed driven gears in constant mesh with said triple idler gear simultaneously rotatable thereby at various speeds in respect to each other mounted in nested relationship to each other on said driven shaft for free rotation in respect thereto, the said nested driven gears having one end face thereof flush in respect to each other, the low and intermediate speed driven gears having beveled notches in said end face thereof, the high speed driven gear having square shouldered notches in said end face thereof, low speed axially disposed ratchet stops in said gear selector unit normally engaging said low speed driven gear at the beveled notches therein, intermediate speed axially disposed ratchet stops and high speed square shouldered axially disposed stops in said gear selector unit constantly urged toward engagement with said intermediate and high speed driven gears at the beveled and square shouldered notches therein, and a plurality of axially reciprocating cams in said gear selector unit responsive to the speed of the driven shaft adapted to permit said intermediate and high speed stops to selectively engage said intermediate and high speed driven gears whereby said driven shaft is rotated by the highest speed driven gear engaged by said gear selector unit.

6. In a variable speed transmission, a drive shaft, an idler shaft and a driven shaft, a driving gear on said drive shaft, a triple idler gear on said idler shaft driven by said riving gear; low, intermediate and high speed driven gears in constant mesh with said triple idler gear simultaneously rotatable thereby at various speeds with respect to each other mounted in nested relationship to each other on said driven shaft for free rotation with respect thereto, an automatic gear selector unit secured to said driven shaft, radially reciprocating cam means in said gear selector unit movable responsive to the speed of the said driven shaft, and axially movable means in the said gear selector unit actuated by said radially reciprocating cam means adapted to engage one of the said driven gears at any one time.

7. In a variable speed transmission, a drive shaft, an idler shaft and a driven shaft, a driving gear on said drive shaft, a triple idler gear on said idler shaft driven by said driving gear; low, intermediate and high speed driven gears in constant mesh with said triple idler gear simultaneously rotatable thereby at various speeds with respect to each other mounted in nested relationship to each other on said driven shaft for free rotation with respect thereto, an automatic gear selector unit mounted on said driven shaft adapted to rotate the same, axially movable means in the said gear selector unit normally urged into engagement with said driven gear, and radially reciprocating cam means movable to predetermined positions in response to the speed of the said driven shaft and adapted to permit only one of said driven gears to be engaged by said axially movable means at any one time.

WILLIAM HARTZ. 

